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Journal of Hand Therapy 28 (2015) 144e150

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Journal of Hand Therapy

journal homepage: www.jhandtherapy.org

JHT READ FOR CREDIT ARTICLE #362.Special Issue

Innovative evaluation of dexterity in pediatrics

Susan V. Duff EdD, PT, OTR/L, CHTa,*, Dorit H. Aaron MA, OTR, CHT, FAOTA b,Gloria R. Gogola MD c, Francisco J. Valero-Cuevas PhD d

a Thomas Jefferson University, Department of Physical Therapy, 901 Walnut St., Suite 510, Philadelphia, PA 19107, USAbAaron & Winthrop Hand Therapy Services, Inc, 2723 Amherst, Houston, TX 77005, USAc Shriners Hospitals for Children, Houston, 6977 Main St, Houston, TX 77030, USAdUniversity of Southern California, Biomedical Engineering Department and Division of Biokinesiology & Physical Therapy, 3710 S. McClintock, RTH 402, Los Angeles, CA 90089, USA

a r t i c l e i n f o

Article history:Received 22 December 2014Received in revised form12 January 2015Accepted 12 January 2015Available online 22 January 2015

Keywords:DexterityMeasurement conceptsFunctional Dexterity TestStrengtheDexterity

* Corresponding author.E-mail address: susan.duff@jefferson.edu (S.V. Duf

0894-1130/$ e see front matter � 2015 Hanley & Belhttp://dx.doi.org/10.1016/j.jht.2015.01.004

a b s t r a c t

Study design: Review paper.Introduction: Hand dexterity is multifaceted and essential to the performance of daily tasks. Timedperformance and precision demands are the most common features of quantitative dexterity testing.Measurement concepts such as rate of completion, in-hand manipulation and dynamic force control ofinstabilities are being integrated into assessment tools for the pediatric population.Purpose: To review measurement concepts inherent in pediatric dexterity testing and introduce conceptsthat are infrequently measured or novel as exemplified with two assessment tools.Methods: Measurement concepts included in common assessment tools are introduced first. We thendescribe seldom measured and novel concepts embedded in two instruments; the Functional DexterityTest (FDT) and the StrengtheDexterity (SD) Test.Discussion: The inclusion of novel yet informative tools and measurement concepts in our assessmentscould aid our understanding of atypical dexterity, and potentially contribute to the design of targetedtherapy programs.

� 2015 Hanley & Belfus, an imprint of Elsevier Inc. All rights reserved.

Introduction pediatrics and introduce innovative concepts embedded within the

Clinicians examine dexterity to gauge skill level and change inperformance after hand surgery or rehabilitation. Differences inproficiency based on age, development, hand dominance, cognitionand clinical conditions are verified through assessment. The pur-pose of this paper is to review measurement concepts integral topediatric dexterity testing and introduce concepts that are seldommeasured or novel as exemplified with two assessment tools.

The terms “dexterity” and “manipulation” have many defini-tions and connotations. In children dexterity and manipulationskills change with development which also presents a challenge totheir assessment. Therefore, it is critical that the clinician select anduse a tool that can quantify, and is sensitive to changes in thecomponents of dexterity of clinical interest in the developing child.Our objective is not to advocate for a specific dexterity assessmenttooldas this depends on the scientific and clinical purpose ofmeasurement. Instead, we review features of dexterity and mea-surement concepts that are integral to common tools validated in

f).

fus, an imprint of Elsevier Inc. All

design of a few sample instruments.

Dexterity measurement

Dexterity can be measured by observing task performance,recording from a checklist or using a standardized assessment tool.Common features of standardized tools are timed performance andprecision. The time for task completion is often measured in sec-onds or minutes using a timer.1,2 Precision is illustrated by theexpectation to place small rings on thin pegs as in the PurduePegboard Test.3 Table 1 outlines features of dexterity testingmeasured with common tools that have normative values forchildren. Normative reference values are useful with pediatricpopulations, where it is important to distinguish between expecteddevelopmental changes and the effects of intervention.

Features of dexterity that are not often measured or are moredifficult to measure include: 1) rate of completion; 2) in-handmanipulation; and 3) dynamic force control. For example, in-hand manipulation has been explored but not fully integratedinto dexterity testing (see Table 1). To better understand the valueof including innovative measurement concepts in our assessments,

rights reserved.

Table 1Features of common pediatric dexterity tests with normative data

Dexterity test Pediatric norms Timed test Precision In-hand manipulation Time to administer

Box and Block4e6 6e19 years Yes Yes No <5 mina

Grooved Pegboard Test1,7 3e20 years Yes Yes Yes e rotation of peg >5 minJebsen Taylor Hand Function Test6,8 6-19 years Yes Yes e stack checkers Yes e rotation of spoon >5 minNine Hole Peg Test1,2 3e20 years Yes Yes Yes e rotation & translation of peg

assessed e not validated9,10<5 min

Purdue Pegboard1,3,6,11,12 2.6e5.11 years, 5e15 years,14e19 years

Yes Yes No <5 min

a <5 ¼ less than 5; >5 ¼ more than 5; min ¼ minutes.

S.V. Duff et al. / Journal of Hand Therapy 28 (2015) 144e150 145

we will review the concepts and describe a few dexterity tests thatincorporate them.

Rate of completion and in-hand manipulation

In addition to measuring the time to task completion, perfor-mance can be expressed as a rate of task completion (i.e., speed).13

This scoring strategy allows for statistically valid numerical com-parisons against other quantitative functional variables and graph-ing of rate of completion along a continuous age scale. Althoughuseful, this scoring strategy is rarely used in dexterity testing.

In-hand manipulation (IHM) is defined as movement or adjust-ment of an object as it is held with one hand.13 Although there areother taxonomies for IHM,14e16 the classification scheme byExner17,18 is described here by three main features: shift (move-ment across finger pads), translation (finger-to-palm and palm-to-finger), and rotation (simple and complex). The three componentsof IHM are assessed with the task of picking up a coin and placing itin a vertical slot. In this example, shift is displayed when we movethe coin across the finger pads. Palm-to-finger translation isdemonstrated when we move the coin from the palm to the fingerpads. Finally, complex rotation is illustrated when we turn the coinon its axis with the fingers before placement in a slot.

IHM develops between 18 months and 7 years of age.17,19 By 3years of age, IHM has developed to the point that standardizedtesting can be reliably performed.9,10,18 IHM is required to completethe Functional Dexterity Test (FDT).13,20

Functional Dexterity Test (FDT)The Functional Dexterity Test (North Coast Medical, Gilroy, CA)

is a timed pegboard instrument.20 The FDT is not new but employsthe unique concepts of rate of completion and in-hand manipula-tion that are not commonly measured. When validated in adults,the FDT had excellent test-retest (ICC ¼ 0.95) and intra-rater

Fig. 1. A: The FDT can be easily administered to very young children, allowing for longiturequired.

(ICC ¼ 0.91) reliability.20 When compared against performancetests that assess activity and participation, it had the highest ratingsfor clinimetric quality.21 Adult FDT normative reference values arepublished20 and were recently updated.22 Pediatric normativevalues are also available.13

The FDT consists of 16 cylindrical pegs (4 cm � 2.2 cm) arrangedin four rows of four pegs each (Fig. 1). It requires a tripod pinch andtwo aspects of IHM: rotation and shift. Participants turn over all pegs(rotation) in a specified order by manipulating each peg with thefinger pads (shift). Participants complete one practice trial and thesecond trial is timed. Results are recorded as the number of pegscompleted divided by time elapsed (pegs/time). This calculation of atest score provides a measure of speed.23 The original FDT scoringinvolved assessing penalties and adding their point values to the testcompletion time to arrive at a final score.20 Even though the pen-alties were subsequently modified for children,24 they provedinadequate. As grasp and movement patterns develop, a trueassessment of pediatric penalties would require a menu of changing,age-specific items, which hampers the ease of test administration.Inefficient movements are reflected in decreased speed, thus do notrequire the additional adjustment for penalties.13 The FDT is sensi-tive enough to detect functional inefficiencies of IHM; therefore,penalties have been eliminated from pediatric FDT scoring.

Normative FDT speed (pegs/sec) for the dominant and non-dominant hands among typically-developing children increaseslinearly with age at a constant rate of 0.037pegs/sec/year between 3and 17 years of age (Fig. 2).13 There are no gender differences through17 years of age. Dominant hands are faster than non-dominant handsat all ages and the difference between the two remains constant.

Presenting normative values as a “growth chart” of FDT speedversus age facilitates easy visualization of expected speed for anygiven age using a continuous age scale. The use of regression onfractional age provides a more precise estimate of performancethanwould be possible by presenting the data in a table grouped by

dinal evaluation into adulthood. B: An unimanual 3-jaw chuck prehension pattern is

Fig. 2. Normative FDT scatterplot showing speed as pegs/second (pps) versus age. Thecontinuous “growth chart” style (versus arbitrary age groupings) allows for moreprecise comparison to typically-developing children 4e17 years old. Dominant handsare shown in red, non-dominant hands in blue.13 (For interpretation of the referencesto color in this figure legend, the reader is referred to the web version of this article.)Permission to reprint from Gogola et al13 was received.

S.V. Duff et al. / Journal of Hand Therapy 28 (2015) 144e150146

arbitrary age ranges. Clinicians who treat children are accustomedto this “growth chart” format for tracking height and weight. It hasalso been successfully used to report pediatric hand strength.25,26

Based on linear regression analysis, age and hand dominance canpredict speed. The available norms allow clinicians to compare bothspeed and rate of change over time of pediatric clients against thenorms for typically-developing children.

The FDT has been used in children to assess dexterity after pol-licization27 (surgically replace an absent thumb with a functionalfinger)28e30 and performance in children with congenital condi-tions. We used the FDT to assess the unaffected hands of childrenages 4e17 years of age with unilateral congenital differences andfound that the unaffected hands were slower than the age-matchednorms (unpublished). The results revealed that dexterity in theunaffected hands of unilaterally affected children does not developat the same rate as typically-developing peers, thus strengtheningthe notion that contralateral hands should be included in

Fig. 3. A) Four springs used for a pediatric version of the Strength-Dexterity Test.35 Note thminiature load cells mounted on either end of the spring over plastic end caps. The compreslateral pinch to compress and hold the spring at the maximal compression force without bPermission to reprint from Dayanidhi et al37 was received.

therapeutic programming. Currentwork includes instrumenting theindividual FDT pegs with wireless inertial sensors equipped with anaccelerometer and gyroscope in order to acquire movement data(smoothness, jerk, and accuracy) in addition to speed.

The FDT is an example of a tool that requires IHM and measuresthe unique feature of rate of completion. It is easy to administer andaccommodates a child’s short attention span and clinical timeconstraints. It reliably measures the performance of young childrenwith and without congenital hand differences. Finally, it can detectsubtle deficits missed with visual observations or simpler grasp andrelease dexterity instruments.

Dynamic force control

Hand-held dynamometers and pinch meters have been usedextensively to quantify normative and clinical levels of static gripand pinch strength.31 Unfortunately, these measures of forcemagnitude are not informative of the dexterous capabilities of theperson as they include the potential confounds of motivation, painavoidance, etc. Interestingly, Lee-Valkov and colleagues24 foundthat in typically-developing children pinch strength correlatedpoorly with dexterity based on the FDT. In addition, the prehensileforces necessary to engage in activities of daily living (ADL) aresurprisingly low.32 Therefore, although clinically useful for otherreasons, maximal static force magnitude may not be an essentialcomponent of dexterity measurement.

Skilled grasp and manipulation of objects requires grading offingertip forces to prevent slips and breakage.33 We grade grip(squeeze) and load (lift) force in advance of object contact (antici-patory control) and modify these forces based on somatosensoryfeedback duringmanipulation.34 Fingertip forcemagnitude and therate of onset are usually low when we grasp a potato chip and in-crease when we lift a full glass of water. In adults, grip and loadforce increase in a parallel, synergistic manner. Conversely, youngchildren increase fingertip forces sequentially,35 exhibiting longdurations for each phase of the grip-lift task. This suggests thatearly in development a feedback strategy dominates.35 After twoyears of age, both feedback and anticipatory control strategies areevident by the display of parallel increases in force and shorterphase durations during manipulation of static objects.35

Dynamic manipulation (as opposed to grip-lift tasks) requiresthat the direction and magnitude of fingertip force vectors becontinuously modified to maintain object stability during taskperformance.36e38 As dexterity develops, the quality of

e SD Test shown is a particular instance of the SD paradigm (Fig. 4). B) In this SD Test,sion requires force magnitudes <3 N. The task requires a two-finger palmar pinch or auckling.

Fig. 4. The StrengtheDexterity paradigm uses a two-dimensional plane34 to explicitlydistinguish the contribution of strength from dexterity requirements. The materialproperties and geometry of the springs can be adjusted to be more or less prone tobuckling (unstable), or more or less stiff. Stiffer springs increase the strengthrequirement (x axis). More slender springs increase the dexterity requirement (y axis).As shown in Vollmer et al,45 springs in the lower range of the strength requirement(<3 N) can be appropriate for pediatric and clinical use. They allow the quantificationof dexterity (i.e., the neuromuscular ability to stabilize an unstable object prone tobuckling with the fingertips) while requiring little strength. Figure adapted fromValero-Cuevas et al,36 Vollmer et al,45 and Talati et al.50

Permission to reprint from Dayanidhi et al37 was received.

Fig. 5. Representative sample of fingertip forces during steady state compression for asingleholdusing theSDtest.35 Theredstar represents the start and theblack star theendofsteady state at maximal compression during the 5s hold. (For interpretation of the refer-ences to color in thisfigure legend, the reader is referred to thewebversion of this article.)Permission to reprint from Dayanidhi et al37 was received.

S.V. Duff et al. / Journal of Hand Therapy 28 (2015) 144e150 147

manipulation is influenced by the task goal and our ability tomaintain stability of the grasped object by aptly responding toperturbations or task dynamics.39e41 Improvement in dynamicmanipulation progresses into late adolescence, as influenced by thedevelopment of the neuromuscular system, experience and gains insensorimotor control.37,40,42,43

Themethod used to capture the capacity to gradefingertip forcesis basedon the informationdesired. Indirect assessment canbedonethrough task performance such as stacking checkers during theJebsen Test of Hand Function.8 Objective measurement of perfor-mance on static grip-lift tasks usually involves laboratory-basedinstruments equipped with single or multi-axial force trans-ducers.43 Dynamic manipulation must be assessed by the ability toregulate fingertip force vectors to control unstable objects.36e38

While a measure of dynamic force control would be useful, thechallenge is how to quantitatively measure it in the clinic.

StrengtheDexterity TestTo quantify the dynamic regulation ofmagnitude and direction of

fingertip forces, Valero-Cuevas et al36 developed the StrengtheDexterity (SD) paradigm using an SD device. The SD Test has beenused to assess hand dexterity in typical and atypical adults36,38,41,44

and children.37,40,45,46 Although it is not yet commercially available,details of the SD device are described in previous publications.36e38,41,44e51 In the SD Test, individuals use the fingertips tocompress a slender and compliant spring that is prone to buckling(Fig. 3).52 Buckling is a form of instability, which becomes exacer-bated as the spring is compressed further. Note that the forcemagnitudes needed to compress the spring to the limit of instabilityare very low, on the order of <3 N. Retaining control of the springrequires dynamic regulation of the magnitude and direction of thefinger movements and fingertip force vectors. To obtain quantitativedata, the compression spring can be fit with two miniaturecompression load cells (ELB4-10, Measurement Specialties, Hamp-ton, VA) to record dynamic compression forces, as depicted in Fig. 3.The maximal level of compression (units of force) is indicative of themaximal level of instability that the neuromusculoskeletal system isable to control.37,38 This metric serves as an informative measure ofneuromotor control for dexterous manipulation.

In the SD paradigm, the mechanical design of the spring de-termines the force magnitudes needed to compress it to the limit ofinstability.36 The current SD Test expands upon work in pediatricpopulations,45 with the current version designed to require verylow force magnitudes c. 2e3 N.37,38,52 The SD paradigm wasdeveloped to explicitly separate the dexterity and strength re-quirements of the task as described in Valero-Cuevas et al36,50 andshown in Fig. 4 from Dayanidhi et al.37

Obtaining a dexterity score using the SD Test requires in-dividuals compress the spring in a controlled, self-paced manner tothe point of maximal compression without slippage or uncon-trolled buckling.37 Participants familiarize themselves with thistask (w10 repetitions) until they exhibit compression for �5 s(Fig. 5).37,46 After familiarization, individuals complete a minimumof 10 trials/hand while sustained compression force is recorded.The mean sustained grip force for three maximal trials is used tocalculate the dexterity score in grams of force (gmf).37

The quantification of sensorimotor skill needed to stabilize ob-jects using the dexterity score exemplifies the features of dynamicforce control and precision.37,46 Results from this research havebeen used to better understand the local and distributed neuralmechanisms associated with maturation, muscle contractilespeeds, functional neural connectivity and neural networks acrossgender, age and clinical populations.37,44e51 Results from a pediatricpopulation are shown in Fig. 6. Work is in progress to bring the SDparadigm into clinical practice.

Dexterity assessment and ADL function

Measures of dexterity should relate to activities of daily living(ADL) and quality of life. Dexterity tests fall within the Body,Functioning, Structure and Activity Domains of the InternationalClassification of Function for Children and Youth (ICF-CY, Organi-zation)53 depending on the specific features and scoring strategyused. A limited number of studies in adults have been conducted toexamine the relationship of findings on dexterity testing to ADL inthe Activity Domain of the ICF framework. Poole and colleagues54

report a reduction in dexterity as measured by the Nine-Hole PegTest and Grooved Peg Test. These findings were associated withperceived difficulty in ADL and a need for greater assistance basedon the Functional Status Index.55 Aaron and Stenick-Jensen20 reportthat the FDT scores correlated with ADL tasks that require a 3-jawchuck (3-fingered pinch), such as buttoning or tying a knot in adultswith hand injuries. Improved individual performance of a specificfunctional task, employing a 3-jaw chuck, predicted a lower

Fig. 6. Dexterity score from children 4e16 years of age on the SD test shown to depict the significant change in performance across age. A. The regression line (CI e 95%) on a Fourierrobust fit is shown in green/magenta, respectively. Data in A and B are colored by gender (blue, girls; red, boys), with individual regression lines for each. Significant increase indexterity score by adjacent age groups were found across childhood and into late adolescence as indicated by asterisks (P � 0.05), SSE ¼ sum of squared residuals; RMSE ¼ rootmean squared error; CI ¼ confidence interval. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)Permission to reprint from Dayanidhi et al37 was received.

S.V. Duff et al. / Journal of Hand Therapy 28 (2015) 144e150148

performance time on the FDT. The relationship between perfor-mance on ADL tasks and the Nine-Hole Peg Test, the FDT or othertools has not been examined in children.

The SD paradigm measures a dimension of sensorimotor capa-bility different from strength, whole-arm motion, and reach-to-grasp behavior.45 Thus, the SD Test’s assessment of a child’sability to stabilize objects is unique and informative. Studies areneeded that relate performance on the SD Test for children to selectADLs requiring dexterity and manipulation.

Summary

The evaluation of dexterity in a pediatric population requiresconsideration of the developmental level of the child and theclinical condition being evaluated. These factors influence the skilllevel and dexterity we should expect, thus directing us to theappropriate assessment tool. Although the number of tests avail-able continues to grow, it is important to closely examine the fea-tures of dexterity that the tool measures and the measurementconcepts involved in scoring. Innovative scoring strategies arecharacteristic of tools such as the FDT and SD Test. The FDT iscommercially available with pediatric normative data,13 while theSD Test is being examined for clinical utility. As the data becomesavailable, the SD Test could provide the pediatric clinician with aunique outcome measure of dynamic force control.

Obtaining a comprehensive view of dexterity requires admin-istration of a combination of assessments. For instance, the com-bined use of the FDT and SD Test could provide measures of rate ofcompletion, in-hand manipulation, and dynamic force control.Validation of common and novel assessments employing uniquescoring strategies will add to our understanding of the underlyingmechanisms of atypical dexterity and provide pediatric clinicalpractitioners and researchers with information useful in the designof targeted interventions.

Acknowledgments

This publication was supported by a grant from the EuniceKennedy Shriver National Institute of Child Health and HumanDevelopment of the National Institutes of Health under awardnumber T32HD064578. Research reported was supported by

National Institute of Arthritis and Musculoskeletal and SkinDiseases of the National Institutes of Health under award numbersR01AR050520 and R01AR052345 to FVC. The content is solely theresponsibility of the authors and does not necessarily represent theofficial views of the National Institutes of Health.

Disclosures: FVC holds US Patent No. 6,537,075 on some of thetechnology used, but has no active or pending licensing agreementswith any commercial entity. None of the other authors have anyfinancial or personal relationships with other people or organiza-tions that could inappropriately influence this work.

References

1. Wang Y-C, Magasi SR, Bohannon RW, et al. Assessing dexterity function: acomparison of two alternatives for the NIH toolbox. J Hand Ther. 2011;24(4):313e321.

2. Poole JL, Burtner PA, Torres TA, et al. Measuring dexterity in children using theNine-hole Peg Test. J Hand Ther. 2005;18:348e351.

3. Wilson BC, Iacoviello JM, Wilson JJ, Risucci D. Purdue pegboard performance ofnormal preschool children. J Clin Neuropsychol. 1982;4:19e26.

4. Fess EE. Functional tests. In: Skirven TM, et al., eds. Rehabilitation of the Handand Upper Extremity. 6th ed. Philadelphia, PA: Mosby; 2011:159.

5. Jongbloed-Pereboom M, Nijhuis-Van Der Sanden MWG, Steenbergen B. Normscores of the box and block test for children ages 3e10 years. Am J Occup Ther.2013;67(3):312e318.

6. Yancosek KE, Howell DA. Narrative review of dexterity assessments. J HandTher. 2009;22(3):258e269.

7. Bryden PJ, Roy EA. A new method of administering the Grooved Pegboard Test:performance as a function of handedness and sex. Brain Cogn. 2005;58(3):258e268.

8. Taylor N, Sand PL, Jebsen RH. Evaluation of hand function in children. Arch PhysMed Rehabil. 1973;54(3):129e135.

9. Pehoski C, Henderson A, Tickle-Degnen L. In-hand manipulation in youngchildren: rotation movements. Am J Occup Ther. 1997a;51(7):744e752.

10. Pehoski C, Henderson A, Tickle-Degnen L. In-hand manipulation in youngchildren: translation movements. Am J Occup Ther. 1997b;51(9):719e728.

11. Gardner RA, Broman M. The purdue pegboard: normative data on 1334 schoolchildren. J Clin Child Psychol. 1979;1:156e162.

12. Mathiowetz V, Rogers SL, Dowe-Keval M, Donahoe L, Rennells C. The PurduePegboard: norms for 14- to 19 year-olds. Am J Occup Ther. 1986;40(3):174e179.

13. Gogola GR, Velleman PF, Zu S, Morse AM, Lacy B, Aaron D. Hand dexterity inchildren: administration and normative values of the functional dexterity test.J Hand Surg Am. 2013;38(12):2426e2431.

14. Bullock IM, Dollar AM. Classifying human manipulation behavior. IEEE Int ConfRehabil Robot. 2011;2011:5975408.

15. MacKenzie CL, Iberall T. The Grasping Hand. Amsterdam; New York: North-Holland; 1994.

16. Pont K, Wallen M, Bundy A. Conceptualising a modified system for classifica-tion of in-hand manipulation. Aust Occup Ther J. 2009;56(1):2e15.

S.V. Duff et al. / Journal of Hand Therapy 28 (2015) 144e150 149

17. Exner CE. In-hand manipulation skills. In: Case-Smith J, Pehoski C, eds.Development of Hand Skills in the Child. Rockville MD: AOTA; 1992.

18. Exner CE. In-hand manipulation skills. In: Case-Smith J, ed. OccupationalTherapy for Children. St Louis: Mosby; 2001.

19. Exner CE. Development of hand functions. In: Pratt PN, Allen AS, eds. Occu-pational Therapy for Children. 2nd ed. St. Louis: Mosby; 1989.

20. Aaron DH, Stegink Jansen CW. Development of the Functional Dexterity Test(FDT): construction, validity, reliability, and normative data. J Hand Ther.2003;16:12e21.

21. Schoneveld K, Wittink H, Takken T. Clinimetric evaluation of measurementtools used in hand therapy to assess activity and participation. J Hand Ther.2009;22(3):221e236.

22. Satorio F, Bravini E, Vercelli S, et al. The Functional Dexterity Test: test-retestreliability analysis and up-to date reference norms. J Hand Ther. 2013;26(1):62e67.

23. Velleman PF, Hoaglin DC. Exploratory data analysis. In: APA Handbook ofResearch Methods in Psychology. vol. 3. 2012.

24. Lee-Valkov PM, Aaron DH, Eladoumikdachi F, Thornby J, Netscher DT.Measuring normal hand dexterity values in normal 3-, 4-, and 5-year oldchildren and their relationship with grip and pinch strength. J Hand Ther.2003;16:22e28.

25. Molenaar HM, Selles RW, Zuidam JM, Willemsen SP, Stam HJ, Hovius SER.Growth diagrams for grip strength in children. Clin Orthop Relat Res. 2010;468:217e238.

26. Xu S, Morse AM, Lacy B, Baggett S, Gogola GR. Peg restrained intrinsic muscleevaluator (PRIME): development, reliability and normative values of a device toquantify intrinsic hand muscle strength in children. J Hand Surg. 2011;36A:894e903.

27. Lightdale-Miric N, Mueske NM, Lawrence EL, et al. Long term functional out-comes after early childhood pollicization. J Hand Ther. 2015;28(2).

28. Aliu O, Netscher DT, Staines KG, Thornby J, Armenta A. A 5-year intervalevaluation of function after pollicization for congenital thumb aplasia usingmultiple outcome measures. Plast Reconstr Surg. 2008;122:198e205.

29. Kozin SH. Pollicization: the concept, technical details, and outcome. Clin OrthopSurg. 2012;4(1):18e35.

30. Staines KG, Majzoub R, Thornby J, Netscher DT. Functional outcome for chil-dren with thumb aplasia undergoing pollicization. Plast Reconstr Surg.2005;116:1314e1324.

31. Mathiowetz V, Wiemer DM, Federman SM. Grip and pinch strength: norms for6- to 19-year olds. Am J Occup Ther. 1986;40(10):705e711.

32. Smaby N, Johanson ME, Baker B, Kenney DE, Murray WM, Hentz VR. Identifi-cation of key pinch forces required to complete functional tasks. J Rehabil ResDev. 2004;41(2):215e224.

33. Westling G, Johansson R. Roles of glabrous skin receptors and sensorimotormemory in automatic control of precision grip when lifting rougher or moreslippery objects. Exp Brain Res. 1984;56:550e564.

34. Johansson R, Cole KJ. Sensory-motor coordination during grasping andmanipulative actions. Curr Opin Neurobiol. 1992;2:815e823.

35. Forssberg H, Eliasson A-C, Kinoshita H, Johansson RS, Westling G. Developmentof human precision grip I: basic coordination of force. Exp Brain Res. 1991;85:451e457.

36. Valero-Cuevas FJ, Smaby N, Venkadesan M, Peterson M, Wright T. Thestrength-dexterity test as a measure of dynamic pinch performance. J Biomech.2003;36(2):265e270.

37. Dayanidhi S, Hedberg Å, Valero-Cuevas FJ, Forssberg H. Developmental im-provements in dynamic control of fingertip forces last throughout childhoodand into adolescence. J Neurophysiol. 2013a;110:1583e1592.

38. Lawrence EL, Fassola I, Werner I, Leclercq C, Valero-Cuevas FJ. Quantification ofdexterity as the dynamical regulation of instabilities: comparisons acrossgender, age, and disease. Front Neurol. 2014;5(53):1e13.

39. Contaldo A, Cola E, Minichilli F, et al. Object use affects motor planning in infantprehension. Hum Mov Sci. 2013;32(3):498e510.

40. Dayanidhi S, Kutch JJ, Valero-Cuevas FJ. Decrease in muscle contraction timecomplements neural maturation in the development of dynamic manipulation.J Neurosci. 2013;33(38):15050e15055.

41. Racz K, Valero-Cuevas FJ. Spatio-temporal analysis reveals active control of bothtask-relevant and task-irrelevant variables. Front Comput Neurosci. 2013;7:155.

42. Eyre JA. Corticospinal tract development and its plasticity after perinatal injury.Neurosci Biobehav Rev. 2007;31(8):1136e1149.

43. Duff SV, Gordon AM. Learning of grasp control in children with cerebral palsy.Dev Med Child Neurol. 2003;45(11):746e757.

44. Dayanidhi S, Valero-Cuevas FJ. Dexterous manipulation is poorer at older agesand is dissociated from decline of hand strength. J Gerontol A Biol Sci Med Sci.2014;69(9):1139.

45. Vollmer B, Holmstrom L, Forsman L, et al. Evidence of validity of a new methodfor measurement of dexterity in children and adolescents. Dev Med ChildNeurol. 2010;52:948e954.

46. Dayanidhi S. Behavioral, Muscular and Dynamical Changes in Low ForceDexterous Manipulation During Development and Aging. Los Angeles, CA: Uni-versity of Southern California; 2012 (PhD dissertation).

47. Fassola I, Lawrence E, Dayanidhi S, Ko N, Leclercq C, Valero-Cuevas F. Is oste-oarthritis of the thumb strictly a orthopedic condition?In: Proceedings of the 1stInternational Thumb Osteoarthritis Workshop, Newport, RI. 13. 2013:12.

48. Holmström L, Lennartsson F, Eliasson AC, et al. Diffusion MRI in corticofugalfibers correlates with hand function in unilateral cerebral palsy. Neurology.2011;77:775e783.

49. Mosier KM, Lau C, Wang Y, Venkadesan M, Valero-Cuevas FJ. Controlling in-stabilities in manipulation requires specific cortical-striatal-cerebellar net-works. J Neurophysiol. 2011;105:1295e1305.

50. Talati A, Valero-Cuevas FJ, Hirsch J. Visual and tactile guidance of dexterousmanipulation tasks: an fMRI study. Percept Mot Skills. 2005;101:317e334.

51. Venkadesan M, Guckenheimer J, Valero-Cuevas FJ. Manipulating the edge ofinstability. J Biomech. 2007;40:1653e1661.

52. US patent 6,537.075.53. World Health Organization. International Classification of Functioning, Disability

and Health for Children and Youth (ICF-CY); 2014 [cited 2014 Nov 08]. Availablefrom: http://www.who.int/classifications/icf/en/.

54. Poole JL, Nakamoto T, McNullty T, et al. Dexterity, visual perception, and ac-tivities of daily living in persons with multiple sclerosis. Occup Ther Health Care.2010;24(2):159e170.

55. Jette A. Functional Status Index: reliability of a chronic disease evaluation in-strument. Arch Phys Med Rehabil. 1980;61:395e401.

S.V. Duff et al. / Journal of Hand Therapy 28 (2015) 144e150150

JHT Read for CreditQuiz: #362

Record your answers on the Return Answer Form found on thetear-out coupon at the back of this issue or to complete onlineand use a credit card, go to JHTReadforCredit.com. There isonly one best answer for each question.

#1. In addition to reviewing traditional measures of dexterity theauthors discuss the following two novel tools

a. CCF and RSDb. PPR and MLBc. FDT and SDd. MFR and ATT

#2. In selecting measurement tools it is key that the clinician takeinto consideration the

a. developmental level of the patientb. environment of the clinical settingc. wishes of the parentsd. instructions of the surgeon

#3. Traditional features of standardized tools are

a. a sensory and motor componentb. their ease of using and their low cost

c. high sensitivity and low specificityd. timed performance and precision

#4. The authors identify all of the following except _____________as features of dexterity that are not often measured or aremore difficult to measure

a. rate of completionb. in-hand manipulationc. rapid exchange ratesd. dynamic force control

#5. The authors conclude that understanding atypical dexterityshould not contribute to the design of targeted therapyprograms

a. trueb. false

When submitting to the HTCC for re-certification, please batch yourJHT RFC certificates in groups of 3 or more to get full credit.